I was trained in basic knife fighting in the USMC. I think that if you have to pull out a knife to defend yourself then you are already at a serious disadvantage. Use your mind & natural survival instincts to avoid conflict before it occurs. When it comes to fight or flight & you decide to fight, than you better be 110% committed. It should be a genuine life or death situation. Most violent attackers especially groups can sense fear & capitilize on it. If you have to pull out an edged weapon or any weapon for that matter, be prepared to use it. The last thing you want to do in a confrontation is add a deadly weapon to the scenario that otherwise wasnt there; routinely people pull weapons to defend themselves but the weapons get turned around on them. What type/size blade do you carry? Is it legal? Is carrying the blade worth the added hassle from law enforcment? Most people think bigger is better, or carry butterfly/switchblade type knives for the shock & awe value simmilar to pumping a shotgun. As said before some knives are illegal most places, ie switchblade,double edged & anything with a blade longer than 3.5". When choosing a knife, size & strength are important & this is not the time to be cheap. Imagine pulling out that cheap chrome & plastic $10 folding knife & actually going to use it; wouldnt it suck if it broke & or inflicted injury on the wielder. I would opt for a legal mid level ($25-$45) tactical folding knife(easily aquired at Wallmart, Dicks, Cabellas or Bas Pro Shops), remember even if you are within your legal rights for carrying it, you dont want to draw added attention to the police when searched, especially if you may be already trespassing, maybe drinking in public, or in possesion of other illegal substances. Be prepared to loose or ditch a knife if it best suits you, so no need for $200-$400 titanium special forces shit. Carrying a knife as a practical tool while traveling makes perfect sense as well. Do not use your knife as a multitool, keep it to cutting things & maybe cleaning under your finger nails, definately no puncturing cans of food etc. Keep your edge sharp so potentially invest in a simple sharpener. I think common mistakes would be lunging or trying to stab opponents as an initial technique. The knife should be an extention of your arm with a stance simmilar to a boxer, always hold the knife in your strong hand shoulders turned slighty; your weak arm should be forward to block & jab just like boxing. This keeps your weapon as far away from the attacker. Keep a solid grip on your weapon, ther eare many variations of grip & I would suggest a simple hammer grip or icepick. But with most thing sthat you may only get one shot KISS(keep it simple stupid) You should practice some basic parrying/slashing technique, understanding that knife fighting is made up of many small cuts to weaken an opponent idealy on there hands, wrists, arms, eyes,kneck etc . The idea is to weaken the opponent in order to inflict some sort of finishing blow, i DONT SUGGEST THIS ATALL! So no need to get into lunging or kill techniques. Bringing out the knife should hopefully even the odds a bit as long as your attacker doesnt have a knife or other weapon. If you are able to reverse the roles by you being the dominent party, your common sense should start backing up slowly & leaving the situation (not running but cautiously leaving the scene). I know friends who was verbally threatened by another with a firearm outside a bar. My friend pulled his knife & attempted toleave the situation. The guy who started it never had a gun & witnesses called the cops & all they remembered was seeing my friend pull the knife. My friend never did wave or cut the other guy but was still arrested & charged with ab deadly weapon, with his prior criminal record & no money for a lawyer eventually had to take some stupid plea involving probation though he believed to have done the right thing.